WCG200 and World of Warcraft disconnects

Hi all...two nights ago I bought a WCG200 to replace a Motorola Surfboard + Linksys wired router combo that met a horrible fate at the hands of a lightning strike. I like the box so far, except for one really nasty problem.

My wife and I both play World of Warcraft. What we're seeing is that after 15-30 minutes of playing WoW, without fail, the cable connection will abruptly freeze and then drop for a few seconds (the "cable" light will go out, come back on, and the "activity" light will be out for a few more seconds and then begin flashing again). According to my wife, nothing else causes it any problems. I messed around with Microsoft Flight Simulator 2004 online last night for over an hour, no problem. She's surfed the 'Net off and on all day today, no problem. But any sustained attempt at WoW seems to cause the cable connect to drop after no more than 30 minutes.

I've messed with the port forwarding, forwarding TCP port 3724 (the WoW port) to my box, to her box, enabling it, disabling it...nothing seems to help. I'm on comcast.net, if that makes any difference, and I never saw this behavior before with the old Surfboard 5100 and the other Linksys router. Does anybody have any idea what might be causing this?

EDIT: Just played WWII Online for about 45 minutes and it dropped as well. So I don't know if it's a game-specific thing, a router-specific thing, or if Comcast here in Richmond is coughing up hairballs.